Field of the Invention
The present invention relates to apparatus and methods for warning people on opposite sides of visual barriers of a possible collision. The visible barriers may include doors, blind corners, and other visual obstructions around which people move with the possibility of colliding with another person or a movable object carried or rolled by a person. The collisions avoided may involve, for example, people, plates of food, containers of liquids, fragile objects, wheelchairs, carts, carried trays, rolling trays, gurneys, and combinations thereof.
Discussion of Related Art
The opening of doors continues to cause injuries to persons and damage to objects when doors are opened by a person on one side of the door while a person or moving object is on the opposite side of the door. When a person is about to operate a door from one side, they normally cannot determine whether or not a person or movable object carried or pushed by another person is on the other side of the door. As a consequence, the potential exists that the door may strike a person or movable object on the opposite side of the door. Similarly, people moving along or past a visual barrier, such as a wall or screen, may collide with other people or movable objects moving toward them from the other side of the visual barrier. It is therefore desirable to prevent injury and damage when people and/or movable objects approach each other from adjacent areas that are mutually not visible to one another.
One solution to the problem as it relates to adjacent areas on opposite sides of a door is to place a window in the door so that a person about to open the door may observe activity on the opposite side before opening the door. This solution is not practical if the door is intended to provide privacy and/or security. Furthermore, where doors are opened quickly or people are moving quickly, it may be that a visual assessment through a window does not provide sufficient warning of a potential collision. One reason for this is that, the person opening the door must actively look through the window and assess what is observed. This may difficult when the area on the other side of the door is poorly lit or when the person opening the door or the person/object on the other side of the door is moving quickly.
One solution related to adjacent areas around blind corners in hallways and adjacent areas on different sides of other visual obstructions is to place a convex mirror such that people moving from opposite sides of the obstruction can see one another. This solution has the advantages of being simple and inexpensive but suffers form the drawbacks including not functioning well if one or both sides of the obstruction are poorly lit and that it requires each person to actively look at objects in the mirror to determine if anything or anyone is moving or obstructing the opposite side of the visual barrier.
U.S. Pat. No. 6,292,100 discloses a door warning system comprising a sensor for sensing people immediately adjacent to one side of a swinging door and a visual or auditory indicator on the other side of the door to warn a person about to open the door from the other side of the swinging door. A radar sensing unit projects a sensing beam downwardly from a wall adjacent to the door and into a roughly circular area slightly larger than the arc through which the door swings and triggers the indicator if a person is detected in the area. Sensors can be placed in the wall on both sides of the door to activate indicators on opposite sides of the door. The indicators may be located at a position on a wall adjacent a door. The '100 door warning system requires that the sensor be mounted to a stationary wall and modifications to the wall for installation of the sensor and sensor power supply and, in some cases, the indicator and indicator power supply. If the indicator is not mounted in the wall, the door must be modified for mounting the indicator and indicator power supply.
U.S. Pat No. 5,861,806 describes a battery powered indicator for detecting the presence of a person in area behind a door. This is useful, for example, for signalling that a restroom is occupied. The indicator is installed on a door such that a light source on one side of the door provides a visual signal indicating the presence of a person on the other side of the door when the door is closed. The indicator is screwed to a top edge of the door via a mounting bracket thin enough to fit within a pre-existing gap between the top of a door and the door frame. The bracket projects beyond an inside surface of the door enough to support a casing on the side of the door where a person is to be detected. A wire lever extending upward from the casing controls a switch that actuates a switch to confirm that the door is closed. A timer limits the time that the indicator illuminates to conserve battery power. Additionally, a ten second delay between door closing the door any activation of the indicating light prevent false positive signals and conserves battery power. Additionally, a timer is used to turn the indicating light off after a predetermined time to slow battery depletion.
The present invention ameliorates drawbacks associated with existing door collision warning systems and provides for an inexpensive and simple device and method for actively warning of possible a collision resulting from the opening of a door. The invention additionally provides for a collision warning device that detects a condition for possible collision between people and/or movable objects moving toward one another around a blind corner or other visual barrier.